Laura Fabbietti and Bernhard Ketzer new associate members of the ALICE collaboration at CERN

News from Physics Department - 2012-11-28

Dr. Bernhard Ketzer and Prof. Laura Fabbietti at “their” detector

Prof. Laura Fabbietti and Dr. Bernhard Ketzer are new associate members of the ALICE collaboration at CERN. ALICE is the acronym for A Large Ion Collider Experiment, one of the largest experiments in the world devoted to research in the physics of matter at an infinitely small scale. Hosted at CERN, the European Laboratory for Nuclear Research, this project involves an international collaboration of more than 1000 physicists, engineers and technicians, including around 200 graduate students, from 105 physics institutes in 30 countries across the world.

Prof. Laura Fabbietti and Dr. Bernhard Ketzer are faculty members of the Physik-Department at Technische Universität München and at the Excellence Cluster Universe, where they lead their own research groups. They have already developed particle detectors for other experiments at GSI in Darmstadt and at CERN. Those detectors are large area GEM detectors, which are used for TCPs (Time Projection Chambers).

Learn about the news form Laura’s and Bernhard’s own report, which is also found on the ALICE matters web site:

Hello, we are Laura and Bernhard! We lead two research groups at Technische Universität München (TUM), which now became associate member of the ALICE collaboration.

Laura is an associate professor at TUM and the Excellence Cluster ‘Universe’. Her main research interests in the last years have been focused on the study of the Kaon/Hyperon-Nucleon and Kaon/Hyperon-Nucleus interaction.

This is why Laura has spent most of her scientific life at GSI, Darmstadt. In particular, her group planned and realized an experiment to search for exotic states, like deeply bound kaonic states where an antikaon acts as a glue between 2 or more nucleons. In addition, they study the still not solved issue of in-medium potential for kaons and hyperons, focusing on reactions with proton and pion beams at kinetic energies of few GeV of the incoming particles.

Sverre Dørheim

In order to approach these issues, Laura´s group has worked in the last 5 years in collaboration with experimentalists active in the FOPI and HADES collaborations at GSI and various theoreticians dealing with low energy QCD processes, who are helping them in interpreting both the observed signals but also those missing.

Within this project Laura´s group has also been developing some hardware in the past years, including the RICH detector of HADES, and a Silicon detector triggering on Lambda particles. Moreover, in collaboration with the group of Bernhard Ketzer at TUM and other institutions in Europe they built a GEM-TPC prototype which has the largest active volume produced so far.

Bernhard is a Junior Principal Investigator at the Excellence Cluster ‘Universe’, and also leads his own group at TUM, which focuses on the investigation of the structure of hadrons and their excitation spectrum, and on the development of novel fast detectors for high-intensity particle beams.

Bernhard, who was a research fellow at CERN before returning to TUM, has designed and constructed the first large-area GEM detectors for the COMPASS experiment. After that his group extended the technique to utilize a pixel readout suitable for very high particle rates, a prerequisite for the hadron spectroscopy program of COMPASS.

The search for exotic mesons beyond the naive quark-antiquark configuration, which are predicted by QCD, has been one of his main goals in the last years. Here, partial wave analysis can reveal even small contributions to a given final state through interference effects. Indeed, a strong signal was observed for a wave with quantum numbers which cannot consist of a simple quark-antiquark pair. His group is currently investigating to which extent the object found is a real resonance.

In parallel, Bernhard´s group joined the PANDA experiment at FAIR, Darmstadt, where hadrons containing charm quarks will be studied using a high-intensity cooled antiproton beam. Bernhard´s group brought up the idea to use a continuously operating TPC as the central tracker of this experiment, and in collaboration with Laura´s and other groups from Germany and Austria, a prototype TPC with GEM amplification was built and successfully operated in the FOPI experiment at GSI.

This is where the research interests of Laura and Bernhard met. The main purpose of the prototype was to test the feasibility of this technology for the PANDA experiment at FAIR, but we decided to combine this technological effort directly with a physics measurement and hence, after having successfully built our GEM-TPC and commissioned it within the FOPI spectrometer at GSI, we employed it in a 2.5 weeks experiment with a pion beam impinging on different nuclear targets. Like that, we can now investigate in a joint effort at TUM the properties of strange particles in pion-induced reactions.

We are both very excited to apply the technology we have developed in the last years within the GEM-TPC collaboration to the largest TPC of the world. Currently we are focusing on the preparation of an IROC prototype equipped with GEMs and we are looking forward to testing it down in the ALICE pit next year. In Laura´s group, Piotr Gasik (Postdoc) and Martin Berger (PhD student) are working on the ALICE TPC. In Bernhard´s group, Markus Ball (Postdoc) and Sverre Doerheim (PhD student) are joining the efforts, not mentioning numerous technical students in both groups. We are looking forward to a fruitful collaboration with the detector experts in ALICE, and hopefully also to a rich physics harvest with the upgraded detector.